How connected are the Soulblight Gravelords to the Vampire Counts of old?
I have a lore question. As far as I understand, the Warhammer Old World is to AoS what the Horus Heresy is to 40K. It is a complete setting unto itself, but the End Times made it a different part of history that changed the setting into AoS.
Growing up in the mid-2000s, I adored the Vampire Counts, especially the Order of the Blood Dragons. I've been researching into AoS lore and how it connects to the Old World, and there's a gap in my knowledge of how the Vampire Counts became the Soulblight Gravelords.
What I know so far is that, somehow, Nagash returned to the mortal realms, and fought against a massive influx of chaos and the other mortal races as part of the services of Death. By this point, the order of the Blood Dragons had since been destroyed as a formal order during the Siege of the Blood Keep years before, but there was still an Order of Blood Knights loyal to Vlad Von Carstein.
During a siege on Chaos, Walach Harkon gave in and fell to Khorn, resulting in him being slain by Vlad Von Carstein for his betrayal. Now, during AoS, all Vampires are in service to Nagash to a larger or lesser extent, but Blood Knights do tend to keep him at arms length.
What I don't know is to what extent the Vampire Counts of old have gone, and how the Soulblight Gravelords have changed post-end times to what they are in current lore. Any help filling these gaps would be appreciated!